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Which radiometric dating methods are used to determine the ages of rocks?

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A detailed geologic time scale chart displaying Earth's history from the Hadean Eon over 4.5 billion years ago to the present, organized by eons, eras, periods, epochs, and ages with color-coded columns and corresponding dates in millions of years. — Precambrian The stratigraphic chart of geologic time.

Radiometric dating determines the age of rocks and minerals by measuring the ratio of radioactive parent isotopes to their stable daughter products. Because these isotopes decay at a constant, known rate—defined by their half-life—scientists can calculate the time elapsed since a material formed.12

Commonly used isotopic systems for dating rocks include:

Uranium-Lead (U-Pb) and Thorium-Lead: These methods are essential for dating igneous and metamorphic rocks, often utilizing minerals like zircon, monazite, and titanite.32
Potassium-Argon (K-Ar): This method measures the decay of potassium-40 into argon-40 and is widely used for various geologic ages.43
Rubidium-Strontium (Rb-Sr): Frequently used for dating potassium-bearing minerals and felsic whole rocks.3
Samarium-Neodymium (Sm-Nd): Useful for mafic igneous rocks, meteorites, and metamorphic garnets.53
Rhenium-Osmium (Re-Os): Applied to trace minerals in mineral deposits.3

In the context of Precambrian geochronology, where fossil-based correlation is limited, these geochronology techniques—particularly zircon dating—are critical for correlating strata and determining the ages of ancient rocks across continents.62